From the back of the book:
Want to be a Dungeon Master?
Get started or ramp up your skills with this fun and easy guide!

Whether you've already run a few DUNGEONS & DRAGONS games or you've decided to try Dungeon Mastering, this book's for you. Here are all the basics of managing a game in the new 4th Edition plus everything that will take your skills to the next level: how to build a good story, design a great dungeon, craft a campaign, and so much more.